Influence of Interfacial Adhesion on Fatigue of Comaco Composites

Abstract

Fatigue and Izod tests have been carried out on aligned carbon fibre composites in which the cure shrinkage of the matrix was controlled. Both fatigue resistance and toughness correlated with shrinkage pressure. There was negligible loss of Young’s modulus during fatigue, up to 80% of the fatigue life, while the flexural modulus declined continuously during fatigue. A hole, drilled in the specimen, increased in diameter at right angles to the stress during the fatigue. Both rate of flexural modulus decline and rate of increase in hole size correlated with shrinkage pressure. These results are interpreted on the basis of the improvement of the adhesion between fibres and matrix that is brought about by the reduction in resin shrinkage.